Lubricating oil composition



June 6, 1944. L. E. BEARE LUBRICATING OIL COMPOSITION Filed April 5,1941 7 Sheets-Sheet 1 0 7. ow, 0 Z w WJ/ ,O .I W bwgg/f W n 6 1w 0 4 NQAAAQS/ w 0 m m m m m W 0 ATTORNEYS June 6, 1944. L. E. BEARE LUBRICATINGOIL COMPOSITION "r Sheets-Sheet 2 Filed April is, 1941 hw mb be sh sum!Liz W 242 $0; ogre/1 0 fiqzwag INVENTOR leeward f. Beare BY PWWmWMRm'VEJHW ATTORNEYS Jun 1944 E. BEARE 2,350,489

LUBRICATING OIL COMPOSITION I INVENTOR 22 7 e e) 4 9 160w; 558w June 6,1944. L. E. BEARE 2,350,489

LUBRICATING' OIL COMPOSITION Filed April 5, 1941 7 Sheets-Sheet 4fimfimfmm ATTORNEYS June 6, 1944. E. BEARE LUBRICATING OIL COMPOSITIONFiled April 5, 1941 '7 Sheets-Sheet 5 WQR m MXQ ATTORNEYS June 6, 1944.

L. BEARE LUBRICATING OIL COMPOSITION 7 Sheets-Sheet 6 Filed April 5,1941 sure/ :42 rm aqzbaaqj izqzwag '///V 7 l e onard 5 Bears ATTORNEYSJune 6, 1944. 1.. E. BEARE LUBRICATING OIL COMPOSITION '7 Sheets-Sheet 7Filed April 5, 1941 INVENTOR Zeonoraffiwe ATTORNEYS @umin,

Patented June 6, 1944 I UNITED STATES PATENT OFFICE LUBBICATING OILCOMPOSITION Application April 5, 1941, Serial No. 387,014

12 Claims.

- Thisinventlon relates t improvements in lubricating oil compositions.It relates more particularly to compounded petroleum lubricating oilscontaining one or more addition agents which impart corrosiveness to thecompounded oils but wherein the corrosiveness of the compounded oil issubstantially inhibited by the addition thereto of relatively smallproportions of alizarin or of the fatty acid stars of alizarin ormixtures thereof.

The trend of. development in modern machinery, notably in Diesel andother internal combustion engines. has imposed increasing burdens on theoil used-for their lubrication, particularly with respect to operatingtemperatures and pressures. The useful operating lifeof a lubricatingoil in such service is determined in large measure by its thermalstability and by its physical capacity to continue functioning as alubricant at the high temperatures and pressures encountered.

One of the measures of thermal stability is resistance to oxidation anda consequent tendency to form sludge but in another aspect the effect ofthermal instability is determined not only by the extent of oxidation ordecomposition but also by the character of the products of suchdecomposition and oxidation and by the extent and location within theengine or the like of the deposits of such products.

In the Diesel type of engine, for example, the high temperature to whichthe lubricating oil is subjected, particularly at the top of the stroke,frequently causes deposition of sludge and carbon in the groove beforeand behind one or more of the piston rings. consequent sticking of therings rapidly deprives the engine and cylinder wall of properlubrication, inducing excessive wear and frequently scoring of thecylinder wall. For satisfactory lubrication, it is essential that thiscondition be avoided.

Another essential characteristic of lubricatin oil to be used undersevere conditions is the ability to maintain a satisfactory lubricatingfilm between the bearing surfaces at the high temperatures and pressuresencountered. This property of the lubricant is usually characterized asfilm strength.

The operating conditions in certain types of machinery are so severethat the natural characteristics of petroleum lubricating oils have beenfound inadequate for the satisfactory lubrication of these machines overextended periods. In such instances it has been necessary to supplementor alter the natural characteristics of the lubricating oil by theaddition of one or more agents, commonly referred to as addition agents.

Various metal soaps, notably soaps of aromatic stearlc acids such asphenyl stearic acid or mixtures comprising such soaps. have been foundto be particularly effective addition agents.

. For instance, the remarkable advantages derived from the. addition ofrelatively small amounts of certain metal phenyl stearates or mixturesof such phenyl stearates with phenyl stearic acid or stearlc acid ormetal stearates to petroleum lubricating oils have been related inUnited States Letters Patent No. 2,081,075, 2,095,538 and 2,180,- 697 toArnold C. Vobach.

Lubricating oils compounded with such material, as described in saidpatents have a high solvent capacity for sludge of a character formed byoxidation or decomposition of petroleum lubricating oils and renderdeposits of sludge and carbon within the engine soft and friable ratherthan 16 hard and coherent and appear to disintegrate and remove suchdeposits as are formed so that the formation on the piston of carbondeposits hard enough and coherent enough to involve sticking of therings is materially retarded, if not avoided. 20 However. lubricatingoil compositions containme such addition agents have been found to bedecidedly corrosive toward some of the alloy bearings, notablycopper-lead and cadmium-silver alloy bearings, commonly used in internalcombustion engines.

I have discovered that the corrosive action of such lubricating oilcompositions is substantially inhibited by the addition thereto ofrelatively small proportions of alizarin or the fatty acid esters ofalizarin; for example, alizarin stearates, such as alizarin monostearateand alizarin distearate.

Not only are the bearings or the like protected from destructivecorrosion, in accordance with my invention, but other desirablecharacteristics of the lubricating oil compound are materially improved,as will appear from the following detailed description thereof.

As previously noted, certain metal phenyl stearates and mixtures thereofhave proven to be very effective addition agents in lubricating oils.The advantages derived from the use of and the method of preparingcalcium phenyl stearate or mixtures of calcium phenyl stearate andunsaponified 45 phenyl stearic acid or calcium stearate or both and themethod of compounding these addition agents in lubricating oils arefully described in the previously referred to Patent No. 2,081,075.

Also, in the above-referred-to Patent No. 2,095,- 59 538, there aredescribed the advantages derived from the use of and the method ofpreparing and compounding with lubricating oils, calcium phenyl stearateor mixtures of calcium phenyl stearate and calcium stearate modified bythe inclusion 55 of the equivalent of 7-20% stearlc or palmitic acid ormixtures thereof.

A further advantageous type of calcium phenyl stearate addition agent isone containing an amount of calcium greater than that correspond- 60 ingto the neutral soap. It may be prepared, for

of the type referred to above.

example, by neutralizing phenyl stearic acid with such an excess of limeas results in the production ofga soap mixture consisting of one part ofbasic calcium phenyl stearate to four parts of neutral calcium phenylstearate. This mixture of neutral and basic soap is herein designatedbasic calcium phenylstearatefl 1 The calcium phenyl stearate additionagen wherein the phenyl stearic acid or mixture of phenyl stearic acidand fatty acid are completely neutralized, no excess of lime over thatcorresponding to the neutral soap being present, is herein designatedneutral calcium phenyl stearate. That in which the phenyl stearic acidor mixture of phenyl stearic acid and fatty acid are not completelyneutralizedbut contain an equivalent of 7-20% excess phenyl stearic acidor palmitic or stearic acid are herein designated acidcalcium phenyistearate.

. References herein to phenyl stearic acid or to calcium phenyl'stearate are to be interpreted as meaning the material or materials sodesignated in the above-referred-to'patents to Vobach. 4'

Each of these calcium phenyl stearate addition agents, i. e. acid,neutral and basic, has been found to be very effective with respect tocarbon deposition, as above noted. However, lubricating oil compoundedwith eitherhas a decided In accordance withmy present invention, thecorrosive action of such lubricating oil compounds is substantiallyretarded or even eliminated without destroying the desirablecharacteristics imparted to the compound by the corrosion-inducingaddition agents. This is accomplished by in-.

corporating in the lubricating oil composition relatively smallproportions of one or more of the previously named corrosion-inhibitingcompounds. Alizarin is relatively insoluble in a mineral oil at normaltemperatures, its solubility under such stearate compounds,respectively, both with. and.

conditions ranging from about .02% in highly parailinic oil to about.05% in naphthenic oils.

Alizarin stearates are more soluble and for this reason their use is insome cases preferable to .alizarin. However, other conditions mayinfluence the choice of one over the other as the characteristics of theresulting lubricating pounds difler in some respects.

e The alizarin under some conditions appears to be more effective thanthe alizarin stearatesin inhibiting corrosion but in the presence ofcalcioil comum phenyl stearates there is a tendency for the alizarin toprecipitate out of the oil, probably as calcium 'ali za'rate. .Alizarinstearates are more stable under such'conditions.

Also, alizarin 'stearates appear to have the-add.- ed'function of ananti-oxidant in calcium phenyl stearate' lubricating oil compounds.However,

they do not appear to have this function in imcompounded 0115, thoughalizarin does Further, though alizarin definitely inhibits corrosion inassess-c appear to function as an anti oxidant such compound.

The invention will be runner (released by spe- 'cinc illustration ofapplications of the principles thereof and of. the beneficial resultssoobtained.

The elect-of the addition of alizarin stearate to acid and basic calciumphenyl stearate-lubrieating oil compounds is illustrated by thefollowing Tables I and II inwhich are recorded the results ottests ofacid and basic calcium phenyl without the addition of alizarin stearate.The mineral oil constituent of each such compoundtestedwasasouth'l'exaspaleoil (fromaGuif Coast crude) having a viscosityof about 500 seconds at 100 F. Baybolt Universal and boiling 10% up to700* F. and up to 900 F. approxi-v mately.

As to each sample referred to in Table I, 1.33%

of acid calcium phenyl stearate was compounded with the mineraloil andas to each of those reterred to in Table II, 1.38% of basic calciumphenyl stearate was compounded with the mineral oil. Alizarinmonostearate .was included in these'compounds in the proportionsindicated.

Table] SampleNc.

"percent" None 0.75 0 oxygen as grams 0 compounded oil..." 435..-";-.-.co.- 3.502 2'! Bearing metal loss, coppeolead -.-..--milligrams 23.8 3.0

new 11,

BamplcNo. 5

sum-m monostearate.-.per cent None 0J0 0.2) 0.75 Total oxygen abmrbedRes gramsoi'oom edo --.cc.. 2,560 1,350 12 87 Bearlngmetal Osacoppenhad;

' milligrams" 26.5 15.6 6.0 2.0

The amount of oxygen absorption recorded in the above tables is atnormal temperature and pressure and was determined by the true oxidationtest-the bearing metal, in this case copperlead alloy, being present inthe oil during the test. The test was in each case conducted at .atemperature of 300 F, and the duration of the test was minutes. Thebearing metal losses shown in the above tables were determined from theweight of the pieces of bearing metal present in the true oxidation test,before and. after the test.

The. alizarin monostearate used in ccmpounriing these samples wasprepared. by refluxing 5 parts of dry powdered alizarin in 50 parts oftoluene and adding 6 -parts of' steai'yl' chloride drop by drop over aperiod of ten hours. The extremely slow addition of the latter was anextra precaution against the possible formation of alizarindistearate,'but is not believed to be The alizarin went completely intosolution soon after all of the stearyl chloride had been added. This wasassumed to indicate the substantial completion of the reaction as only asmall fraction of alizarin issoluble in the toluene. The mixture wasrefluxed for an additional ten hours phenyl stearate compounds, itdoesnot 75 88 8 p 'fi flllfi n gainst any 1 mm l mflinillg imdissolved andthe toluene then distilled off to the point at which foaming occurred.The product was then air-dried at 150-200 F. until free from any odor oftoluene. The yield was 104 parts of alizarin stearate which issubstantially the theoretical yield.

The alizari stearate product was a brown, brittle waxy solid, melting atabout 150-160" F. Its analysis showed a trace of chlorine (0.08%) and asmall amount of sulfur (0.12%).

The effect of the presence oi. varying proportions of alizarinmonostearate on the rate of oxygen absorption by the calcium phenylstearate compounded oils, Samples 1 to 6, inclusive, under theabove-described conditions, is graphically illustrated by Figure I ofthe. drawings in which the amount of oxygen absorbed in cubic centimeters, measured at normal temperature and pressure conditions, perhundred grams of the compounded oil, is plotted against time expressedin minutes. From this chart it will be observed that the addition of0.1% of alizarin monostearate to the basic calcium phenyl stearatecompounded oil considerably prolonged the period within which oxygenabsorption was relatively inactive. In other words, it substantiallyinhibited oxidation for a considerable period of time. For example,within the first hour of the test, less than 100 cubic centimeters ofoxygen were absorbed. The addition of larger proportions of alizarinstearate still further increased the period of relative inactivity, 0.2%being even more effective than 0.75%. Such period of relative inactivityoi the compounded lubricating oil, with respect to oxidation orcorrosion, is herein referred to as the induction period.

The effect of the addition of alizarin monostearate to calcium phenylstearate compounded oils is further illustrated by Table III whereinthere is tabulated data concerning tests in which varying proportions ofthe alizarin stearate were added to acid calcium phenyl stearatecompounded oils of the type and composition previously described.

Table III Sample No.

Calcium phenyl stearate.. ...per cent. 1.33 1.33 1.33 Alizarinmouostearate do None 0. 75 0. Indiana sludging time... hours 27 25 26lj, A. S. '1. M.-naphtha insoluble .(io. 43 0 42 lsoosity at 210 F.cudof 50 hours 79 70 73 Viscosity rise at 210 F. in 50 hours 22.1 14. 3 117 100 milligram induction period:

Copper-lead alloy. ...hours 1 14.5 Cadmium-silver alloy -.do... .5 25

1 Approximate.

The Indiana sludging time noted in Table III and elsewhere herein isexpressed in terms of the time required to form milligrams of sludge per10 grams of material tested in a glass cantainer at 341 F. by theIndiana oxidation test described in the Society of Automotive EngineersJournal 34, page 173 (1934). The 1% A. S. T. M. naphtha insoluble figureis the time required to produce, under the same conditions, 1% ofmaterial which is insoluble in A. S. T. M. naphtha. The viscosityfigures are in seconds Saybolt Universal and were taken after a periodof treatment by the said Indiana oxidation test.

The 100 milligram induction period is the t'me required for a loss of100 milligrams in weight oi the particular alloy bearing in contact withthe compounded lubricating oil maintained at 250 1". as determined bythe Chrysler bearing corrosive test-machine.

Similar data, but with respect to neutral calcium phenyl stearatecompounded oils containing different proportions of neutral calciumphenyl stearate and alizarin monostearate. is presented in Table IV:

Table IV Sample No.

Calcium phenyl stearate; per cent. 1.31 1.33 0.67 Alizarln monostearatei do None 0. 76 0.5 Indiana sluding time.... hours 30 24 15 1% A. B. '1.M.naphtha insoluble.. do 44 65 40 Viscosity at 210 F.end of hours.. 7472 Visooslt rlseat 210 F. in50hours....... 13.7 11.6 mill gram inductionperiod:

Copper-lead alloy hours 3.5 42.0 35.5

Cadmium-silver alloy. do .5 62.0 39.5

Data corresponding to that presented in the foregoing tables, but withrespect to basic cal- Table V Sample N 0 l3 14 15 i 16 l 17 18 Calciumphenyl stearate l percent. 1.33 1.33 1.33 0.67 1.0 2.0 Allzarinmonostearate per cent .Noue 0.75 0.5 0.5 0.68 0.68 Indiana sludging timehours 36.5 30.0 32.5 0.0 25.0 40.0 1% A. S. T. M. naphtha ins0l ublehours 49.0 47.0 45.0 39.0 60.0 60.0 Viscosity at 210 F.eud

oi50h0urs... 73.8 60.0 71.01680 05.0 65.0 Viscosity rise at 210 F. in lI -50h0l1l'S........ 17.0 13.2 17.7 15.0 11.0 11.0 100 milligraminduction period:

Copper-lead alloy hours. 4.0 30.5 24.5 31.5 I 51.0 20.0 Cadmium-silveralloy hours. 0.5 41.5 365,510 31.0

Thus, it appears that by the inclusion of various proportions ofalizarin stearate in calcium phenyl stearate lubricat'ng oilcompositions, comprising either acid, neutral or basic calcium phenylstearate, the induction period, i. e. the time required for the initialloss of 100 milligrams of bearing metal by corrosion, is markedlyincreased without in most instances greatly affecting detrimentally thesludging characteristics of the compounded oil.

In each instance the Indiana sludging time was somewhat reduced and insome cases the 1% naphtha insoluble time was slightly reduced while inothers, notably Samples 11. 17 and 18, the latter was materiallyincreased. However, in every instance, except Sample 15, there was adecided reduction in viscosity rise during the 50 hour test period.

Corrosion is also inhibited by the addition of alizarin to the calciumphenyl stearate compounded oils. Where 0.2% alizarin was compounded witha basic calcium phenyl stearate compounded oil, such as described above,comprising 1.33% basic calcium phenyl stearate, the 100 milligraminduction period with copper-lead I greater than 0.75%

bearings was increased to 11 hours and, with cadmium-silver, wasincreased to 30 hours. Alizariml as previously noted, is only slightlysoluble in uncompounded naphthenic base oil. However, it is soluble tothe extent of about .2% in these compounded oils containing 1.33%calcium phenyl stearate, though it is relatively less stable thereinthan is alizarin stearate and has a tendency to form a precipitate attemperatures in the range from 250 to 350 F.

The advantages with respect to inhibition of bearing corrosion derivedfrom the incorporation of relatively small proportions of alizarinstearate in calcium phenyl stearate lubricating oil compounds isgraphically illustrated by Figs. II to IV, inclusive, of the drawingswhereon bearing corrosion loss in milligrams, as determined by theChrysler bearing corrosion test machine, is

plotted against time in hours. These tests were conducted at 2540 R. P.M., 250 F. oil feed temperature and 2700 pounds load.

on Fig. II is shown the rate of bearing corrosion losses of copper-leadand cadmium-silver alloy bearings when using acid, basic and neutralcalcium phenyl stearate compounded oils, respectively, and the decideddecrease in corrosion rate in each where alizarin stearate' isincorporated in the compounded oil. It will be observed that theinduction period was in each instance materially prolonged by theaddition of alizarin monostearate to the lubricating oil composition.

The corrosion-inhibition obtained by the incorporation of variousproportions of alizarin stearate or alizarin in basic calcium phenylstearate compounded oils containing 1.33% basic calcium phenyl stearateis shown on Fig. 111 of the drawings. The effect of varying theproportions of calcium phenyl stearate and alizarin monostearate in thebasic calcium phenyl stearate compound is similarly shown on Fig. IV ofthe drawings.

It was observed that at relative concentrations 7 alizarin monostearateto 1.33% calcium phenyl stearate a dark red precipitate started to format temperatures above 450 F. but that below this ratio no precipitatecompound to which 0.75% alizarin monostearate was added showed noperceptible bearing corrosion loss. Samples 14 and 16 above, whensubjected to this test under more severe conditions (the hot box test),showed, respectively, 190 and 50 milligrams bearing corrosion loss.Comparable piston conditions with respect to'carbon deposition atthe endof the test were obtained in each case.

It is sometimes desirable to include in the lubricating oil compound ofmy invention relatively 'ployed is generally in the range orapproximately 0.5 to 1.0% by weight.

I have discovered that alizarin distearate is generally more stable inlubricating oil compounds containing calciumsoaps than is alizarin orthe mondstearate of alizarin. The distearate appears to equal themonostearate in corrosioninhibitin power but has the advantage over themonostearate that there is a higher critical ra@ 1:10 of the distearateto calcium phenyl stearate permissible before precipitation occurs onheating. Similarly, alizarin alone, in concentrations up to 0.2% in'alubricating oil compounded with basic calcium phenyl stearate, does notcause a precipitate to form on heating. However, on

heating a calcium phenyl stearate compounded oil containing bothalizarin and alizarin distearate, a. slight precipitate may occur.

Illustrations of specific proportions of calcium phenyl stearate, laurylalcohol and alizarin or alizarin stearates which have been found to-giveparticularly advantageous results when compounded with the previouslydescribed lubricating oil-appear in the following Table VI in which.Sample No. 21, which contains no alizarin or alizarin stearate, isincluded for comparison:

Table VI Sample No.

Calcium phenylstearate percent.. 1.33 0.67 1.33 0. 67 1.33 1.33 Laurylalcohol. do 1.0 None 0.5 0.5 1.0 1.0 Alizarln monostearate t 0 75 0 N Nper cen .5 one 0.375 one None Alizarin distearate do' None None NoneNone 0.75 None Aliqann do.--. None None None None None 0.2 Indianasludgmg time hours 28 15 36.5 26 1% A. S. T. M. naphtha insoluble h 5-.40 49 39 Viscosity at 210 F-end 50 ours 72 73.8 69 Viscosity rise at 210F. in

50hours 17.3 17.6 17.6 14.2 100 milligram induction period:

Copper-lead allo ours-- 45 56+ 4 36 11 Cadmium-silver alloy hours 756-]- 0.5 41.5 3015 In compounding the above-referred-to samplesdesignated No. 19 and No. 20, the neutral calcium phenyl stearate wasused while Samples Nos. 21 to 24, inclusive, were compounded with basiccalcium phenyl stearate.

The corrosive characteristics of various compounds included in Table VI,determined as in the tests previously described, are graphicallyillustrated on Figs. V and VI of the drawings with respect tocopper-lead and cadmium-silver alloy 7 bearings, respectivelyincludingfor ready com- ,parison the curve for Sample 8 previously'idenarindistearate increases the tendency to form a precipitate over thatpresent when the distearate small proportions of a solubilizer such aslauryl alcohol. The lauryl alcohol has a stabilizing iniiuence onmineral oil compounds comprising calis used alone, this tendency is notparticularly objectionable in most cases. Further, the presence ofalizarin appears to have an activating eiTect upon the alizarindistearate-which increases the corrosion-inhibiting ability of thedistearate. For example, a compounded oil consisting oi 1.33% basiccalcium phenyl stearate, 1% lauryl alcohol and 1% alizarin distearate inthe above mentioned South Texas pale oil, when subjected to the hot boxtest in a standard one-cylinder Diesel Caterpillar test engine, resultedin a copper-lead alloy bearing corrosion loss of 105 milligrams. In asimilar compounded oil wherein the alizarin distearate proportion wasreduced to 0.75% and 0.1% of alizarin added. the copp lead alloy bearingcorrosion loss was only 50 milligrams. In both cases the piston and ringcondition was excellent with respect to carbon deposition. However, whenthe proportion of alizarin distearate in this compound was reduced toonly 0.5%. the bearingcorrosion loss increased decidediy.

In the regular Caterpillar one-cylinder engine test, the copper-leadalloy hearing corrosion losses, using the alizarinfree Samples No. 7 andNo. 13, were, respectively, 11,900 milligrams and 2860 milligrams whilethat for Sample No. 8. which contained alizarin monostearate. was 420milligrams. In the more severe hot-box Caterpillar engine test, theselosses for compounded oils containing alizarin or alizarin stearate wereas follows:

70 milligrams for Sample No. 19 40 milligrams for Sample No. 20 I 65milligrams for Sample No. 22 170 milligrams for Sample No. 23 100milligrams for Sample No. 24

For the purpose of more clearly illustrating the advantages derived frommy invention, the base lubricating oil used in the foregoing specificexamples has in each case been a South Texas pale oil such as previouslyidentified. However, it will be understood that my invention is notlimited to a particular lubricating oil but is applicable to lubricatingoils generally.

For example, a mixture of 62.5% phenolsolvent-treated neutral oil and37.5% slightly solvent-treated bright stock from a Pennsylvania crudecompounded with 1.33% neutral calcium phenyl stearate, 0.75% alizarindistearate and 0.1% alizarin caused a copper-lead alloy bearingcorrosion loss in the above-mentioned hot box Caterpillar en e test ofonly 60 milligrams. Its Indiana sludging time was 108 hours; its 1% A.S. T. M. naphtha insoluble was 127 hours; and its viscosity rise at 210F. for 50 hours and 100 hours was, respectively, 4.9 and 24.7 seconds.Similarly a mixture of 75% of the previously mentioned Texas pale oiland 25% of an acidtreated high sulfur lubricating oil fractioncompounded with 1.33% basic calcium phenyl stearate, 1.0% laurylalcohol, 0.75% alizarin dlstearate and 0.1% alizarin, when tested on afour cylinder Caterpillar test engine (hot box test) resulted in anaverage copper-lead alloy bearing corrosion loss of only 43 milligrams.In this test, the piston skirt was clean. the rings were free and therewas only a very light carbon deposit in the top groove. Its 100milligram induction period with copper-lead alloy .bearings was 40hours. 7

Nor is the utility of my invention limited to calcium phenyl stearatelubricating oil compounds. I have found it of decided advantage wherethe calcium phenyl stearate is supplemented by still further additionagents and also where the calcium phenyl stearate is replaced by othercorrosion-inducing addition agents. For

. example, decidedly beneficial results have been obtained bycompounding with the previously referred to South Texas pale oil 1.33%basic calalloy hearings of 47 hours. On a four-cylinder Caterpillar testengine (hot box test) the average copper-lead alloy bearing corrosionloss was 117 milligrams and the piston condition with respect to carbondeposit was good.

similarly, a compound consisting of South Texas pale oil, 4% of asolution in mineral oil of the calcium soap of oxidized mineral oilabout equal in calcium content to 1.33% of calcium phenyl stearate,0.75% alizarin distearate, 0.1% alizarin and 2% sulfurized sperm oil wasfound to have a 100 milligram copper-lead alloy bearing induction periodin excess of 51 hours. In a four-cylinder Caterpillar test engine hotbox test, '15 using this latter compound, the copper-lead alloy bearingcorrosion loss was 55 milligrams and the piston condition with respectto carbon deposition was excellent.

I will further illustrate my invention with rem spect to lubricating oilcompounds wherein aluminum phenyl stearate or phenyl stearic acid issubstituted for the calcium phenyl stearate previously referred to. Withaluminum phenyl stearate, the above-mentioned tendency for the formationof a precipitate under certain conditions is substantially reduced and amore stable composition under such conditions is obtained. Theapplication of my invention with respect to the inhibition of oxidationand corrosion by the addition of alizarin to aluminum phenyl stearate orfree phenyl stearic acid lubricating oil compounds is illustrated by thefollowing Table VII. In the compounded oils illustrated, the lubricatingoil constituent was the previously mentioned South Texas pale oil. Testsof samples containing no alizarin are included for comparison:

Also, a compounded oil consisting of the South Texas pale oil with 1%aluminum phenyl stearate and 0.5% alizarin showed no appreciable signsof corrosion of copper-lead alloy bearings by the Chrysler bearingcorrosion test.

Though alizarin is only slightly soluble in lubricating oil at roomtemperatures, it was in complete solution at the temperatures of thesetests.

Lubricating oil compounds containing aluminum phenyl stearate or phenylstearic acid are normally decidedly corrosive but, as appears from theabove-tabulated results, the inclusion of very small proportions ofalizarin materially inhibits corrosion. It appears that the alizarinacts as a true corrosion-inhibitor in such compounded oils. However,alizarin does not appear to act as an anti-oxidant in the compounds ofTable VII as the oxidation rate was reduced by the addition of alizarinonly to about that of the base oil without the bearing metal present. minstance, a

further test of the compounded oil containing 1.0% phenyl stearic acidbut no alizarin showed a metal loss of 49.8. milligrams due'to corrosionand a total oxygen absorption of about'640 c. 0.

metal present. Also', Sample 81 above had a reduced oxidation rateduring the first part of the test, but closely approximated that of thealizariniree compound during the latter part of the oxidation period.

. While'I do not predicate my invention upon any theory of the action ofalizarin, it would appear that allzarin protects the metal from thecorro- 'sive action of the addition agent. I have observed.

that metal which has previously been subjected to the action oi.compounded oils containing alisarin is much more resistant to corrosionthan bearings which have not been so treated For example, the samecopper-lead alloy bearing used:

in the above test of Sample 30 was subsequently tested with Sample 28and the resulting. bearing corrosion loss was only 18 milligrams ascompared with.49.8 milligrams loss of the bearing not so treated.

The corrosion-inhibiting power of alizarin with respect to normallycorrosive compounded oils containing aluminum phenyl stearate. isgraphically illustrated by Figure VII of the drawings as to copper-leadand cadmium-silver. alloy bear- .ings. The curves for the alizarin-jfreeoils are also included for ready comparison. a 7

In addition to the advantages" derived from my invention with respect tocorrosiomithe lubricating oil compound is frequently also improved withrespect to its sludging and film-strength characteristica' Forinstance,the addition of 0.5% of alizarin monostearate to a compounded oilconsisting of a highly refined steam-distilled double-solvent-treatedresidual oil from a Pennsylvania c'rude, having a viscosity ofapproximately 126 seconds .at 210 F. Saybolt Universal'and 1.25% of themethyl ester of a fatty acid produced by the oxidation of mineral oil,was found to improve materially the sludging characteristics,

of said compounded oil and substantially to decrease the viscosity riseof thecompounded oil when subjected to the Indiana sludging test.

The fllm strength of Sample 13, for instance, 7

'stearate.

was 418 pounds as determined by th Timken breakdown test. The additionoi 0.2% v aliz arin increased this breakdown. load to 22 pounds and theaddition of 0.75% alizarin stearate, together with 0.2% alizarin.further increased the breakdown load to 24 pounds. Similarly, Sample 24which contained 0.2% alizarin had a Timken breakdown load of 22 poundsas compared with 18 pounds for Samplelii. v 1

Iclaim: a

, 1. An improved lubricating oil compound com;

prising a petroleum lubricatingv oil, ametal soap of an aromatic fattyacid in an amount suilicient to impart corrosiveness to said lubricatingoil com- I pound and a compound of the groupconsisting of prising apetroleum lubricating oil, phenyl stearic acid in an amount sufiicientto impart corrosiveness to said lubricating oil compound and a compoundof the group consisting of alizarin and 1:5 fatty acid esters thereof inan amount suillcient as compared with 90 c. c. for the oil without theto inhibit said corrosiveness.

4. An improved lubricating oil compound comprising a petroleumlubricating oil, calcium phenyl stearate in an amount suficient toimpart l corrosiveness to said lubricating oil compound and a compoundof the group consisting of all:- arin and fatty acid esters thereof inan amount sumcl'ent to inhibit said corrosiveness.

5. An improved lubricating oil compound'com is prising a petroleumlubricating oil, calcium phenyi steal-ate in an amount sumcient toimpart corrosiveness to said lubricating oil compound and a compound oithe group consisting of aiizarin. alizarin monostearate and alizarindistearate in an amount suficient to inhibit said corrosiveness.

6. An improved lubricating oil compound comprising a petroleumlubricating oil, aluminum phenyl stearate in an amount suflicient toimpartborrosiveness to said lubricating oil compound and a compound ofthe group consisting :of alizarin, alizarin monostearate and aliz'arindiistearate in an amount suiiicient to inhibit said. corrosiveness. j Q

a I. An improved lubricating'oil compound comprising a petroleumlubricating 011. DherLvl stearic acid in an amount suflicient toimpart'corrosiveness to said lubricating .oil compound and seem: poundof the group consisting of alizarin, alizarin monostearate and alizarindistearate inv an 5 amount suillcient to inhibit said corrosiveness.

8. An improved lubricating oil compound comprising a petroleumlubricating oil, calcium phenyl stearate in an amount suillcient toimpart corrosiveness to said lubricating oil compound. a solu- 40bilizer and a compound of the group consisting of alizarin, alizarinmonostearate and alizarin distearate in an amount sufllcient to inhibitsaid corrosiveness.

9. An improved lubricating oil compound comis prising a. petroleumlubricating oil and an addition agent which imparts corrosiveness tosaid lubricatingo'il compound, the corrosiveness of the compounded oilbeingsubstantially inhibited by the addition of an effective amount of10. An improved lubricating oil compound comprising a petroleumlubricating oil andanaddition'agent which imparts corrosiveness to saidlubricating oil compound. the corrosiveness of so the compounded oilbeing substantially inhibited by the addition of eflective amounts of,aliza anda fatty acid ester of alizarin. i 11.'An improved lubricatingcompound comprising a petroleum lubricating oil, a metal soap go of anaromatic fatty acid in an amount suflicient to impart corrosiveness tosaid lubricating oil compound, the corrosiveness of the compounded oilbeing substantially inhibitedby the addition of an eifective' amount ofan alizarin stearate.

.65 12. An improved lubricating oil compound comprising a petroleumlubricating oil, andaimetal soap of an aromatic fatty acid in an amountsu'ill-' I cient to impart corrosiveness to said lubricating oilcompound, the corrosiveness oi the com-'- pounded oil-beingsubstantially inhibited births addition of effective amounts of alizarlnanda fattyacidesterofalizarin.

